High seafood consumption has also been linked to infertility, according to researchers from Hong Kong.

In 2002, the Chinese University of Hong Kong reported on a study involving 150 infertile couples undergoing IVF, and 26 fertile couples.

Researchers linked high levels of mercury in the bloodstream with infertility in men and women. Sharks and other deep-sea fish are known to accumulate mercury in their tissues.

On the mainland, infertility is also rising - possibly due to pollution. It was reported last year that during the past two decades, the infertility rate climbed from 3 per cent - among the lowest in the world - to 12.5 per cent, close to the 15-20 per cent range in developed countries.

'China's infertility rates will continue to rise,' says Mo Shuzhen, director of the infertility service at Beijing Minzu Hospital. 'Environmental factors and social practices brought about by an increasingly hectic lifestyle will drive the numbers up. Nowadays, many married women delay having children because of lifestyle pressures, and I've seen plenty who complain of infertility later in life.'

Pollution has also been blamed for a rise in male infertility.

More than 10 per cent of the 300,000 couples wed in Zhejiang each year are unable to conceive a child, Xinhua reported last year.